Television transmitter tube



N0v.12, 1940. KNQBLUCH ETAL 2,220,964

TELEVISION TRANSMITTER TUBE Filed Jan. 21, 1938 AATTORNEY Patented Nov.12, 1940 UNITED NSTATES PATENT OFFICE TELEVISION SMITTER TUBEApplication January 21, 193s, serial No. 186,020

In Germany November 11, 1936 l `2 Claims.

This invention relates to improvements in the construction of televisionpicture transmitter tubes of the Iconoscope type wherein aphotosensitive mosaic is used and wherein the mosaic 5 is systematicallyscanned by a cathode ray beam.

When such tubes. are used, diiiiculties are occasionally encountered inthe production of undistorted signals from the signal plate oi the tubebecause of theY fact that the mosaic screen may have become warped ordistorted in the course of the thermal treatments to which the tube issubjected during its manufacture. The mosaic screen should be even andflat in order that clear reproductions of the image may be possible.When the mosaic `screen is warped and not flat, it is difficult toproperly and sharply focus the image to be televised upon the mosaic,with the result that proper details and definition of the image to betransmitted to a distant point is prevented or reduced.

Now, accordingl to this invention, with a View to obviating the saiddifficulty, the mosaic screen of the television transmitter tube is soconstructed as to ybe inherently `free, from twist and warp,

that is, it is made in such a way that even when subject to an intenseheat treatment it will stay planar and even; inside the vacuum vessel itis rigidly secured only at one point.

A number of exemplified embodiments of the invention shall be explainedmore fully in what follows by reference to the schematic representationsof the drawing, wherein:`

Figures 1 and 2 show respectively a sectional and plan view of oneimproved form of construction of the mosaic.

Figure 3 shows, somewhat schematically, the location of the mosaic inthe transmitter of tube.

Figure 4 shows in detail one manner in which 40 the mosaic may beattached to the supporting rod.

Figures 5 and 6 show modifications in the manner of attaching the mosaicto the support member.

Figure 7 shows a detail of Figure 6 along lines l--l. f

Unwarped construction of the mosaic screen, for example, may consist asshown in Figures 1 and 2 being two views at right angles to each other.In building up the frame of the screen of angular sheet strips Ill to I3are used, to which are attached triangular pieces of sheeting I4 to Ilwhich are joined to strips Il) to I3 by spot Welding, for example. Intothe resulting frame is inserted a mica lamination VIt which (Clf250-153)'supports particles or spherules oi silver representing the elements ofthe mosaic screen, and

which are shown at Illr on `the left-hand side of the mica sheet I8,while on the right side' is an unbroken metallic coat 20 whichconstitutes 5 what is known as the signal plate. Superposed upon thelatter is another sheet of mica, 2|, and

this is connected with the frame comprising parts I0 to l1. This, forinstance, may be effected b-y pressure-connectingl smallsheet-metal 10angle pieces 22 in the four cornersofthe frame and, if` desired, theymay also be placed in the middles of the sides of the `frame against themica lamination 2l, connection with the parts l to I3 being establishedby spot welding, for 1.5 instance. The metal layer 20 which serves asthe signal plate must, of course, 'be provided Witha lead or conductor;this has not been indicated in detail in the drawing.

Before going into the details of how to secure 20 the screen illustratedin Figures 1 and 2 inside' the vacuum vessel, it shall-be explained byreference to Figure 3 that the screen I0 to 22, upon which the image tobetelevised `maybe projected by the photo-optic objective or lens system23, 25 and which may be scanned or explored by the aid of thecathode-ray pencil or beam 24, is mounted inside the Vacuum vessel.` Thecathode ray beam 2d is generated by a conventional electron gunstructure which produces a narrow beam of elec- 30 trons. Furthermore,the cathode ray beam is deflected by means of electrostatic orelectromagnetic means in order that the screen I0 to 22 may be scanned.Since the structure of cathode ray guns and beam defiecting elements isold 35 `in the art, these elements are not specifically shown in thedrawing. The glass vessel or bulb 25 has on its top what is called acup-shaped lead-in depression or bay as indicated at 26 to which a glassrod 2l is` welded or fused.

Now, to this glass rod may be attached the warp-proof screen in amanner, for example, as shown in Figure 4, by using a clip or two stripsof sheet metal laid around the rod as indicated at 28 and V29. To thesestrips is `attached an 45 angle piece 30, which, in turn, is attached asby spot welding to the side of the screen II. A rigid connection is`established between the screen and the glass rod by securing the anglepiece 30 to the strips 28 and 29 by rivets or by 50 spot welding. Now,if the dimensions of the screen should undergo an expansion during thethermal treatment, the screen itself will stay perfectly even.`

Another mode of securing the screen to the 55 supportl is illustrated inFigure 5. Attached to the glass rod 21, which, for the sake of clarityof representation, is shown only in part, there is rigidly connected apiece of wire 3l which is welded to the frame member l2 at one endthereof as shown in front in Figure 5. The other end of the Wire'ispermitted to slide in a bore or opening 33 in the frame member I3.member I 0 is attached by means of a strip of sheet metal 34 to theglass rod 21 in such a Inanner that sliding and also a certain amount ofrotation are feasible. Now, in the course of the thermal treatment anyexpansion of the screen in the direction of the piece ofwire 3| willresult only in a'small amount of sliding of the frame member I3 upon thewire 3l, and rotational stresses are relieved by a slight turn about theaxis A-B. An extension of the screen in the direction of the rod 21causes sliding of the sheetmetal strip 34 or the wire 3| on the rod 21,and

also in this case the smooth and even form of light-rays, is caused toimpinge upon the oppothe screen will be preserved.

Y Figures 6 and 7 illustrate an arrangement which is particularly suitedfor the so-called bilateral or double sided image scanners, that is tosay, for image scanners in which the charge or electrical pattern isproduced by the means disposed upon one face of the mosaic screen, whilethe neutralizing or releasing pencil, which may be a pencil o1' beam ofcathode-rays or of site face of the same screen. The screen 35 whichcomprises mosaic elements which extend all the way through the screen(being here shown only schematically) is rigidly attached on a U- shapedglassrod 35 only at one corner 31 by the aid of a clip. At the-left-handtop corner is provided a clip 38 which is capable of a sliding movementin verticaly direction, and upon the right-hand side of the screen asingle forkshaped guidev device is provided; the latter being capable ofa sliding motion in the direction of the right-hand side of the screen35 as well as in a `direction at right angles thereto. In Figure Theframe '1 is shown a fork-shaped supporting member which comprises twostrips of sheet metal 39, 40, which are welded or riveted fast to thescreen 35 f and which span the glass rod 36.

It is claimed:

1. In a television transmitter tube, a planar light-sensitiverectangular electrode, an electron beam source, means for scanning saidelectrode with said beam, means for supporting the electrode in the tubewhich includes a pair of support arms for the electrode, means forrigidly securing a point along one edge of the electrode to one of thesupport arms, means for sildably securing another point along said oneedge of the electrode to the said one supporting arm to permit movementof the electrode relative to and along the said arm at the lastmentioned point, and means for slidably securing the opposite edge ofthe electrode to the other arm to permit bi-lateral movement thereofwith respect to the said other arm whereby unequal changes in thedimensions o-f the electrode and the support arms may be alleviated,said opposite edge being supported solely by said slidably securingmeans.

2. A television transmitter tube, a rectangular light-sensitive mosaicsurface, an electron beam source, means for scanning said electrode withsaid beam, means for supporting the surface of the tube which includes aU-shaped support member, means for securing one edge of the surface toone of the arms ofthe support member at a plurality of points, at leastone of said securing means being rigid, Whereas the remaining securingmeans are slidable, and means for slidably securing the opposite edge ofthe surface to the other arm of the support member for bi-lateralmovement with respect to the last mentioned arm, wherebyiexpansional andcontractional stresses in the mosaic surface may be alleviated, saidopposite edge being supported solely by said slidably securing means.

HENNING KNOBLAUCH. WERNER KLUGE.

